Move platform_thread to base/threading and put in the base namespace. I left ...

base/threading/platform_thread_mac.mm

Index: base/threading/platform_thread_mac.mm
===================================================================
--- base/threading/platform_thread_mac.mm	(revision 70321)
+++ base/threading/platform_thread_mac.mm	(working copy)
@@ -1,8 +1,8 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "base/platform_thread.h"
+#include "base/threading/platform_thread.h"
 
 #import <Foundation/Foundation.h>
 #include <dlfcn.h>
@@ -32,8 +32,6 @@
   }
 }
 
-}  // namespace base
-
 // static
 void PlatformThread::SetName(const char* name) {
   // pthread_setname_np is only available in 10.6 or later, so test
@@ -52,3 +50,5 @@
   // See http://crbug.com/47058
   dynamic_pthread_setname_np(shortened_name.c_str());
 }
+
+}  // namespace base